Disclosed is a mobile device (15) for analysing breath samples, comprising:—at least one mouthpiece (16) provided with at least one inlet opening (17) and at least one outlet opening (21) for allowing a person to respectively inhale and exhale via the mouthpiece,—at least one air filter (20) connected to the mouthpiece for filtering ambient air to be inhaled by the person,—at least one analysis compartment (19) connecting to the outlet opening of the mouthpiece and provided with at least one chemical trace detector (1), wherein the chemical trace detector comprises: at least one semi-conducting sensor (2)； at least one heating element (4) for heating the semi-conducting sensor； at least one processor (6) for controlling the heating element； and a detection circuit (7) for detecting the change in resistance of the semi-conducting sensor which is at least partially determined by the presence of at least one chemical trace which reacts in the presence of the semi-conducting sensor.
